Backlight modules are configured to display backlit for display modules within display devices. The light-emitting performance of the backlight module may directly affect the display performance of the display module.
Referring to FIG. 1, a conventional backlight module 1 includes a light emitting diode (LED) lamp set 101, a light guiding plate 102, a diffuser 103, a top prism sheet 104, and a down prism sheet 105. The top prism sheet 104 and the down prism sheet 105 are respectively stacked on the diffuser 103. FIGS. 2-4 are schematic views of the diffuser 103, the top prism sheet 104, and the down prism sheet 105. The diffuser 103 includes a protrusive portion 1031 arranged in a front section. The down prism sheet 105 includes two ear portions 1051 arranged in the front section. Referring to FIG. 5, when the components are stacked, a black single-sided adhesive may be adhered to the protrusive portion 1031 of the diffuser 103 and the ear portions 1051 of the down prism sheet 105. The down prism sheet 105 may be fixed by the two ear portions 1051. However, there are two gaps between the protrusive portion 1031 of the diffuser 103 and the two ear portions 1051. On one end of the diffuser 103 close to the lamp set 101, the light beams emitted by the light guiding plate 102 may pass through the gaps to arrive a display panel, which may result the light leakage as indicated by arrow A in FIG. 5. As such, the bright lines may exist on the display panel and the display performance of the display device may be affected.